In the manufacture of integrated circuits (ICs) and other electronic devices, testing with automatic test equipment (ATE) is performed at one or more stages of the overall process. A special handling apparatus is used to place the device under test (“DUT”) into position for testing. In some cases, the special handling apparatus may also bring the DUT to the proper temperature and/or maintain it at the proper temperature to be tested. The special handling apparatus is of various types including “probers” for testing unpackaged devices on a wafer and “device handlers” for testing packaged parts; herein, “peripheral” or “peripherals” will be used to refer to all types of such apparatus. The electronic testing itself is provided by a large and expensive ATE system. The DUT requires precision, high-speed signals for effective testing; accordingly, the “test electronics” within the ATE, which are used to test the DUT, are typically located in the test head, which must be positioned as close as possible to the DUT. The test head is extremely heavy; the size and weight of the test heads have grown from a few hundred pounds to as much as three to four thousand pounds.
In order to use a test head to test integrated circuits, the test head is typically “docked” to a peripheral. When docked, the test head must be located as close as possible to the peripheral's test site in order to minimize signal degradation. A test head positioning system may be used to position the test head with respect to the peripheral and may be designed to facilitate flexible docking and undocking of a test head with a variety of peripherals. A test head positioning system may also be referred to as a test head positioner or test head manipulator.
The test head is typically mounted in a cradle, which allows the test head to pivot so that it can be aligned with the peripheral. Thus, to assure proper orientation, it is desirable for the test head to be able to pivot compliantly within the cradle. A top view of a test head in a cradle is shown in FIG. 24A, where test head 110 is situated within cradle 200. In other words, cradle 200 is situated around test head 110. Side views are shown in FIGS. 24B through 24D. In FIG. 24B, test head 110 is oriented horizontally relative to cradle 200. As shown in FIGS. 24C and 24D, test head 110 may be rotated counterclockwise or clockwise from a horizontal position. Again, in this manner, the docking surface of test head 110 may be oriented to be parallel with the reciprocal docking surface of the peripheral, which is not shown.
In some applications, particularly as test heads have become more complex, the width of test head 110 may be substantially large. Thus, due to physical restrictions imposed by the peripheral, test head 110 may be so large that there is simply no room to have a cradle situated on the sides of the test head. While test head mounting schemes which support the test head with pivot mechanisms contained inside the test head are known (WIPO WO 01/04644 and WIPO WO 02/025292), these have the undesirable property of occupying valuable volume inside the test head that could be required for test electronics.